This invention relates to optical connectors and connector plugs therefor for creating an electrical and/or optical indication of the condition of the connector relative to the adapter.
Optical fiber transmission systems are becoming widely used in the transmission of signals such as data, voice and the like, and in many instances, are replacing traditional electrical systems. Many of the arrangements common to electrical systems, such as coupling, interconnection, splicing, and the like have their counterparts in optical systems but, because of the totally different characteristics of the transmission media, i.e., optical fiber versus metallic wire, connectorization, splicing, and the like, a quite different apparatus is involved. Where, for example, it is necessary to make a great number of connections in one location, both systems may use what is referred to in the art as patch panels, which provide arrays of connector adapters for interconnection, but the interconnections themselves are generally quite different.
It is common practice in the optical connector art to terminate a length of optical fiber with a connector, an example of which is the SC type connector that is shown and described in U.S. Pat. No. 5,212,752 of Stephenson et al. There are numerous types of such fiber terminating connectors, and, inasmuch as there has been some effort directed to standardization, each type of connector generally requires a different coupling arrangement to permit interconnection of two fibers, for example. The SC and LC connectors are becoming more and more popular, and the remainder of the discussion, in the interest of simplicity, is devoted to such connectors. It is to be understood that the following description of the principles and apparatus of the invention is applicable to other types of connectors as well. As is shown in the Stephenson et al. patent, an SC connector includes a ferrule assembly including a barrel having a collar at one end and an optical fiber terminating ferrule projecting from the barrel. The ferrule assembly is disposed in a plug frame such that an end portion of the ferrule projects from one end of the frame. The plug frame is configured to snap lock into a grip member having a locating key thereon, and the grip is inserted into one side of a slotted coupler adapter, with the locating key inserted into the slot. The grip of a corresponding SC connector is inserted into the other side of the adapter so that the ends of the ferrules abut each other to form a low insertion loss optical interconnection. In the SC connector, the ferrules are spring loaded longitudinally to insure contact between the fiber containing ferrule ends. The entire interconnect operation involves linear motion only and results in a low insertion loss, mechanically stable, protected junction between the two fibers. The expenditure of time in making the interconnection is small and the operator or installer is relieved of having to perform anything other than simple linear motion in plugging the connectors into the coupling adapter. The LC type connector also involves only linear motion and results, when in its adapter, in low insertion loss, mechanical stability, and a protected junction.
In virtually any connector arrangement, however, there is potentially a safety hazard that can be present. Where one or more of the pre-connectorized fibers is carrying optical energy, such energy can be emitted from the end of the fiber connector and pass through the unoccupied buildout block or coupling adapter to the side of the panel where connections are to be made. This optical energy can be harmful for the operator or installer and can be especially harmful to his or her eyes. This hazard is most prevalent when an active connection has to be repaired, cleaned, or otherwise altered by removing an existing connectorized fiber and replacing it with another. In such an instance, it might be difficult or otherwise impractical to shut off the signal transmission in that particular fiber circuit, hence the installer is forced to deal with a light emitting junction or connection. The danger to the operator or installer becomes greater as the optical power is increased, which is a present aspect of the art, where higher and higher optical power, e.g, greater than one watt, is being transmitted. This hazard has long been recognized and there are numerous arrangements in the prior art for blocking any light emanating from a fiber connection through an open adapter. In U.S. Pat. No. 5,678,268 of Stephenson, et al., there is shown a pivotable optical shutter arrangement wherein a normally closed pivotable shutter blocks the open exit of an adapter when a connector plug is removed. The shutter advantageously requires only one motion to open it to permit insertion of a plug or connector into the adapter. Such a shutter as shown in the patent is operable by only one hand instead of prior art arrangements which generally require awkward use of two hands by the installer. One of the disadvantages of any shutter arrangement however, is that they are easily xe2x80x9cdefeatablexe2x80x9d in that they can be, during installation of large numbers of connectors and in the interest of expedition, for example, temporarily fixed in the open position, thus contravening their purpose. In addition, the fiber optic transmission art has progressed to the use of higher and higher light energy or power, and has reached a point where shutter arrangements in general have, because of the high light energy, become transparent to much of that energy in the form of infra-red light, which is commonly used. Where the light intensity is very high, actual damage to the optical connector and the associated fibers can occur.
In the aforementioned co-pending U.S. patent application of Lampert, the disclosure of which is incorporated herein by reference, several embodiments of the invention therein are shown, each being based upon a sensing mechanism in the adapter for signaling whether the adapter has a connector plug therein or when the adapter is vacant or empty. The signal thus generated is applied to a control circuit which activates or de-activates the laser which supplies optical power through the fiber to the connection. The laser is de-activated when the adapter has no connector plug therein, and is activated when there is a connector plug in place within the adapter. Included in that disclosure are embodiments which sense the impending insertion or removal of the connector plug from the adapter. Several of the embodiments shown in that application rely, for signal generation, on active devices, such as LEDs and detectors or Hall effect devices whereas a simpler arrangement not involving active devices would lessen the possibility of malfunction and would lend itself readily to systemwide standardization.
The present invention is an optical fiber connector plug wherein the plug, when inserted into an adapter having sensors therein causes a signal for activating the light source, such as a laser, produced after a sensing mechanism determines that the connector plug is fully seated in its operative position within the adapter, and the signal ceases upon indication to the sensing mechanism that the connector plug is about to be removed from the adapter. In this way the light from the fiber end never passes through an empty adapter. The connector plug of the invention is usable with any of a member of adapters having sensing means therein adapted to respond to the insertion of removal of the plug. In the following discussion, the sensing mechanism comprises first and second spaced electrical contacts.
In greater detail, the LC connector plug, for example, has a cantilevered latching arm on the connector plug for latching the plug to the adapter in the operative position in a known arrangement. The latching arm has first and second latching shoulders protruding laterally therefrom and the adapter has first and second spaced latching ribs, the undersurfaces of which bear against the latching shoulders and cam the latching arm down as the plug is being inserted. The ribs extend part of the way into the adapter and form latching stops at their inner ends which are spaced a predetermined distance apart. When the latching shoulders reach the ends of the ribs, the arm snaps upward, bringing the shoulders to bear against the latching stops at the rib ends to maintain the plug in its operative position. The plug can then only be removed by the latching arm being depressed sufficiently to remove the latching shoulders from contact with the latching stops.
In one embodiment of the invention, the latching stops have conductive material on the rib ends, thereby forming first and second electrical contacts which make up a sensing mechanism. The latching shoulders on the latching arm are spaced the predetermined distance apart and are formed by a metallic bar extending transversely through the latching arm, which, when in contact with the latching stops when the plug is fully inserted, shorts the two electrical contacts together, thereby completing a control circuit for turning on the light source. The circuit is completed only when the connector plug is fully seated, and, when the latching arm is depressed for removal of the plug, the circuit is immediately broken. Thus, the laser or other light source can only be on when the connector plug is fully seated within the adapter in its operative position and hence, there can be no light passing out of a vacant adapter.
Similar operative features may be adapted to other types of connector-adapter combinations. The features of the invention are most readily apparent from their embodiment in an LC type connector as set forth in the following detailed description, although the principles and features thereof are applicable to other types of connectors as well.